1. Field of the Present Invention
The present invention relates to urethral valves, and more particularly to a magnetic actuation urethral valve adapted for inserting into the urethra of a patient who suffering from urinary incontinence in order to recover control of urine flow.
2. Description of Related Arts
Urinary incontinence is a common and serious problem that may be caused by old age, some forms of neurological dysfunction or injuries, or prostate and bladder surgeries. Such problem is hard to treat or, generally, incurable. Patients suffering from this problem not only may experience discomfort and embarrassment, but also may lose some normal human activities.
Many efforts have been taken to solve this problem. Use of indwelling catheters and associated bags often leads to infections of the bladder because the catheter provides a direct passage to microorganisms into the human body. Use of diapers is uncomfortable and embarrassing. Use of artificial urethral sphincters needs surgical implantation that is expensive, complicated, and has a low success rate, sometimes leading to serious complications. Use of various kinds of urethral valve for non-surgical insertion into the urethra is a simple, low-cost, and easy-to-accept way to recover urinary continence.
U.S. Pat. Nos. 4,909,785 and 5,112,306 introduce a device for valving urine involving a flexible tubular body with a drainage canal therethrough, which includes collapsible means for blocking the passageway of urine. It is manually actuated to an open position by means of pressing the flexible valve body. It also includes means for closing the valve automatically after a period delay in which allows voiding of the bladder. The structure of this device is complicated while its size is considerably large.
There are a few different types of magnetic actuation urethral valves such as U.S. Pat. Nos. 3,812,841, 5,004,454, and5,140,999. These devices have some basic properties in common. They are all magnetic in nature and respond to a magnetic fields generated at the exterior of the body. They all need a bias from a spring to maintain their closed position. Their differences are present mainly in the forms of the interactions between the magnetic valve and the controlling magnetic field.
In U.S. Pat. No. 3,812,841, the valve member is pulled directly by external force. The magnet in the valve must be large enough in size to get enough pulling force from the controlling magnetic field against the bias to open the valve. Due to the weak pulling force from direct attraction, it does not work reliably and increases the possibility of malfunction of the unit and consequential repair or replacement. Furthermore, its physical size presents extreme difficulties in insertion and removal.
U.S. Pat. No. 5,004,454 is much simpler and smaller in size then U.S. Pat. No. 3,812,841. Instead of using direct pulling force to open the valve member, it takes the mechanical advantage by using a lever to gain more force to open the valve member than the direct attraction. Because of the efficiency of this mechanism, the size of the magnet in the valve can be reduced. The lever is the valve member itself in a special shape inside the valve body. The valve body limits the range of the lever and the valve that is actuated is quite small, so that urine flow is reduced to a trickle.
U.S. Pat. No. 5,140,999 is very similar to U.S. Pat. No. 5,004,454. The main progress made by U.S. Pat. No. 5,140,999 is that there is an actuator rod which extends out of the valve body and into the bladder, providing greater torque and range for opening the valve. One problem of this design is that the valve might leak when the patient moves tremendously such as running or jumping due to the vibration of relatively long actuator rod with a magnet on its top. Another problem is the possibility of formation of bladder stones caused by a foreign object, which is the extending actuator rod inside the bladder.